let forEachPoint = function (func) {
  return function (input, opt_output, opt_dimension) {
    let len = input.length;
    let dimension = opt_dimension ? opt_dimension : 2;
    let output;
    if (opt_output) {
      output = opt_output;
    } else {
      if (dimension !== 2) {
        output = input.slice();
      } else {
        output = new Array(len);
      }
    }
    for (let offset = 0; offset < len; offset += dimension) {
      func(input, output, offset)
    }
    return output;
  };
};

let gcj02 = {};
let i = 0;
let PI = Math.PI;
let AXIS = 6378245.0;
let OFFSET = 0.00669342162296594323;  // (a^2 - b^2) / a^2

function delta(wgLon, wgLat) {
  let dLat = transformLat(wgLon - 105.0, wgLat - 35.0);
  let dLon = transformLon(wgLon - 105.0, wgLat - 35.0);
  let radLat = wgLat / 180.0 * PI;
  let magic = Math.sin(radLat);
  magic = 1 - OFFSET * magic * magic;
  let sqrtMagic = Math.sqrt(magic);
  dLat = (dLat * 180.0) / ((AXIS * (1 - OFFSET)) / (magic * sqrtMagic) * PI);
  dLon = (dLon * 180.0) / (AXIS / sqrtMagic * Math.cos(radLat) * PI);
  return [dLon, dLat];
}

function outOfChina(lon, lat) {
  if (lon < 72.004 || lon > 137.8347) {
    return true;
  }
  if (lat < 0.8293 || lat > 55.8271) {
    return true;
  }
  return false;
}

function transformLat(x, y) {
  let ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));
  ret += (20.0 * Math.sin(6.0 * x * PI) + 20.0 * Math.sin(2.0 * x * PI)) * 2.0 / 3.0;
  ret += (20.0 * Math.sin(y * PI) + 40.0 * Math.sin(y / 3.0 * PI)) * 2.0 / 3.0;
  ret += (160.0 * Math.sin(y / 12.0 * PI) + 320 * Math.sin(y * PI / 30.0)) * 2.0 / 3.0;
  return ret;
}

function transformLon(x, y) {
  let ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
  ret += (20.0 * Math.sin(6.0 * x * PI) + 20.0 * Math.sin(2.0 * x * PI)) * 2.0 / 3.0;
  ret += (20.0 * Math.sin(x * PI) + 40.0 * Math.sin(x / 3.0 * PI)) * 2.0 / 3.0;
  ret += (150.0 * Math.sin(x / 12.0 * PI) + 300.0 * Math.sin(x / 30.0 * PI)) * 2.0 / 3.0;
  return ret;
}

gcj02.toWGS84 = forEachPoint(function (input, output, offset) {
  let lng = input[offset];
  let lat = input[offset + 1];
  if (!outOfChina(lng, lat)) {
    let deltaD = delta(lng, lat);
    lng = lng - deltaD[0];
    lat = lat - deltaD[1];
  }
  output[offset] = lng;
  output[offset + 1] = lat;
});

gcj02.fromWGS84 = forEachPoint(function (input, output, offset) {
  let lng = input[offset];
  let lat = input[offset + 1];
  if (!outOfChina(lng, lat)) {
    let deltaD = delta(lng, lat);
    lng = lng + deltaD[0];
    lat = lat + deltaD[1];
  }
  output[offset] = lng;
  output[offset + 1] = lat;
});

let sphericalMercator = {}

let RADIUS = 6378137;
let MAX_LATITUDE = 85.0511287798;
let RAD_PER_DEG = Math.PI / 180;

sphericalMercator.forward = forEachPoint(function (input, output, offset) {
  let lat = Math.max(Math.min(MAX_LATITUDE, input[offset + 1]), -MAX_LATITUDE);
  let sin = Math.sin(lat * RAD_PER_DEG);

  output[offset] = RADIUS * input[offset] * RAD_PER_DEG;
  output[offset + 1] = RADIUS * Math.log((1 + sin) / (1 - sin)) / 2;
});

sphericalMercator.inverse = forEachPoint(function (input, output, offset) {
  output[offset] = input[offset] / RADIUS / RAD_PER_DEG;
  output[offset + 1] = (2 * Math.atan(Math.exp(input[offset + 1] / RADIUS)) - (Math.PI / 2)) / RAD_PER_DEG;
});


const projzh = {};

projzh.ll2smerc = sphericalMercator.forward;
projzh.smerc2ll = sphericalMercator.inverse;

projzh.ll2gmerc = function (input, opt_output, opt_dimension) {
  let output = gcj02.fromWGS84(input, opt_output, opt_dimension);
  return projzh.ll2smerc(output, output, opt_dimension);
};

projzh.gmerc2ll = function (input, opt_output, opt_dimension) {
  let output = projzh.smerc2ll(input, input, opt_dimension);
  return gcj02.toWGS84(output, opt_output, opt_dimension);
};

projzh.smerc2gmerc = function (input, opt_output, opt_dimension) {
  let output = projzh.smerc2ll(input, input, opt_dimension);
  output = gcj02.fromWGS84(output, output, opt_dimension);
  return projzh.ll2smerc(output, output, opt_dimension);
};

projzh.gmerc2smerc = function (input, opt_output, opt_dimension) {
  let output = projzh.smerc2ll(input, input, opt_dimension);
  output = gcj02.toWGS84(output, output, opt_dimension);
  return projzh.ll2smerc(output, output, opt_dimension);
};


export {projzh}
